James Comey a leaker; there's no conspiracy with Russians: Donald Trump

US President Donald Trump today branded sacked FBI Director James Comey as a "leaker" and asserted that his testimony before a Senate Committee proved that there was "no collusion and no obstruction" with regard to possible connections to Russia and an ongoing FBI probe.

Trump said he is "100 per cent" willing to testify under oath on Comey meetings and tell the FBI Special Consul Robert Muller that he never asked FBI to stop investigating.

Trump also denied asking Comey for a pledge of loyalty.

"One hundred per cent....I would be glad to tell him (special counsel Robert Mueller) exactly what I told you," Trump said at a joint news press conference in the Rose Garden of the White House with the visiting Romanian President.

Trump was responding to questions on Comey's explosive testimony in which he accused the president of trying to stop a probe into the alleged Russian interference in the US elections last year.

"No collusion, no obstruction, he's a leaker, but we want to get back to running our great country," Trump said.

"Yesterday showed no collusion, no obstruction. We are doing really well," he said.

President Trump, however, refused to say whether his private conversations with Comey were taped.

He said people would know about it very soon. "I'll tell you about that maybe sometime in the near future," he said.

"That was an excuse by the Democrats who lost an election that some people think they shouldn't have lost, because it's almost impossible for the Democrats to lose the Electoral College, as you know. You have to run up the whole East Coast and you have to win everything as a Republican, and that's just what we did," he added.

"So it was just an excuse. But we were very, very happy and, frankly, James Comey confirmed a lot of what I said. And some of the things that he said just weren't true," Trump said.

Earlier, in his characteristic early morning tweet, Trump said, "Despite so many false statements and lies, total and complete vindication... And WOW, Comey is a leaker!"

During his Congressional briefing organised by the powerful Senate Select Committee on Intelligence yesterday, Comey confessed that he leaked the information about his interaction with the US president.

The information was leaked to a reporter of 'The New York Times' through a professor from the Columbia Law School.